The present invention relates generally to analytical techniques used in biochemistry, and more particularly to improved devices and methods for staining electrophoretic gels so as to visualize electrophoresed biological material within the gels.
Electrophoresis is a well known method for analyzing biological materials such as proteins and nucleic acids for various purposes, including for example the diagnosis of disease states in humans and other animals. Generally, electrophoresis involves depositing the biological material of interest on a buffer-wetted porous support medium and applying an electrical field across the support. Because components of the biological sample have varying charges and molecular weights, they migrate at different rates and can therefore be separated by the support.
Most electrophoresed biological materials cannot be immediately visualized within the support and must therefore be subjected to a staining procedure which visually differentiates support areas containing biological materials from those which do not. For example, the staining procedure can render biological materials darker, or lighter, than their surrounding support environment.
One highly useful staining procedure is known as the silver staining method, and involves contacting electrophoresed gels, particularly polyacrylamide gels, with a staining agent including a source of silver ions, and a developing agent including a reducing agent to reduce the silver ions to silver metal. The silver ions are preferentially bound to the biological materials, and thus when the gel is developed a silver pattern emerges from which the relative migration of biological materials can be ascertained. Additional information relative to silver staining and other staining protocols can be found by reference to literature on the subject, including for instance Bassam et al., Analytical Biochemistry 196, 80-83 (1991), and U.S. Pat. Nos. 4,434,234; 4,391,689; 4,575,452; 4,582,808; and 5,064,768.
The processing of electrophoretic gels by presently known and available means is, unfortunately, both a time consuming and labor intensive effort. Accordingly, there is a strong need for improved devices and methods for conveniently and quickly staining electrophoretic gels. It is to this need and demand that the present invention is addressed.